|Dual Core 4|
|Total sleep||4 hours 20 minutes|
|Specification||2 cores and 4 naps in an Uberman configuration.|
DC4, or Dual core 4 is a proposed Dual core schedule, intended as a part of a possible gradual adaptation to Uberman. The configuration of the cores is the same as DC3, but one more nap is added, and sleeps are placed equidistantly similar to Uberman. 
As a Dual core schedule, DC4 shares most characteristics with other schedules in the family, especially DC3. As with DC3, the first core is expected to contain mostly SWS, whereas the second core is expected to contain a mixture of SWS, REM sleep, and light sleep. The first one to two naps are expected to be contain mainly REM sleep, thanks to its position in REM peak. Other naps is likely to contain more light sleep, as well as trace amounts of SWS.
The purpose of DC4 is to transition to Uberman, with 2 core sleeps to eventually be reduced to naps via an intermediate adaptation to E5. To prepare for the transition, all the sleep blocks start at the same time as the target Uberman schedule, in an attempt to entrain the sleep pattern in advance.
Because DC4 is intended to be a transitional schedule to Uberman, it is not considered a long-term schedule. It is also not required to fully adapt to the schedule before transitioning to Uberman, as that would take a long time and not much more likely to be successful. The adaptation process is expected to be similar to that of DC3, or perhaps slightly easier due to the extra nap boosting alertness.
Although DC4 has more sleep than DC3, there has been no successful adaptations to the schedule. Attempts are very rare, as most Uberman attempts are started cold turkey. The inventor of this schedule almost successfully adapted, but had to quit due to unrelated medical issues. It may even be more difficult than DC3, as the extra nap is expected to make it more difficult to fall sleep.
As with DC3, intense SWS and REM sleep wakes during both cores and naps will be frequent during stage 3, and a comprehensive alarm setup is required.
The wake gap between each sleep is too small for many activities, which makes the schedule difficult to sustain lifestyle-wise. The day gaps are similar to the gaps on Uberman, though the naps are expected to be more flexible after adaptation. Careful planning of daily activities like food and exercise will be required. The 3 naps placed in the day will also pose difficulties to those who not in full control of their own time.
DC4 can be used to learn napping skills, being a much more sustainable form of Naptation. It is then advised to recover afterwards, and start a polyphasic attempt without sleep debt. DC4 may also act as a fallback schedule if Uberman or E5 fails, but no one has adapted to the schedule this way.
- "Dual Core Sleep Schedules". polyphasic.net. Retrieved 2020-11-24.